This invention relates to an image display device, and particularly to such a device and method of operating the same in which an electrical discharge is employed to result in an optical output.
There presently exist several display devices which include the use of an electrical discharge for creating an optical output and hence, a desired display. By an electrical discharge device, it is meant a cell which releases energy, partially in the form of light, through the acceleration of electrons and the feedback of electron created species, such as photons or ions, whereby additional electrons are produced.
Among these devices are conventional plasma discharge cells, such as the one shown in U.S. Pat. No. 3,767,968, issued Oct. 23, 1973. Optical feedback and ion feedback discharge cells are other forms of such display devices. Exemplary optical feedback display devices are shown in U.S. Pat. No. 3,825,922, issued July 23, 1974, entitled "Channel Plate Display Device Having Positive Optical Feedback," and in copending application, Ser. No. 636,096, filed Nov. 28, 1975, now U.S. Pat. No. 4,029,984 entitled "A Fluorescent Discharge Cold Cathode for an Image Display Device." Exemplary ion feedback display devices are shown in the following: U.S. Pat. No. 3,904,923, issued to J. Schwartz, Sept. 9, 1975, entitled, "Cathodo-Luminescent Display Panel;" U.S. Pat. Nos. 4,001,619 and 4,001,620 issued to J. Endriz et al., and Endriz, respectively, dated Jan. 4, 1977, each entitled "Modulation Mask for an Image Display Device," and copending patent application, Ser. No. 672,122 of Endriz et al., filed Mar. 31, 1976, entitled, "Parallel Vane Structure for a Flat Display Device."
Although these display devices are suitable for some purposes, they have one common problem: relatively slow addressing time. Rapid addressing is difficult to obtain since each of these devices requires a finite amount of time before the necessary electrical discharge can be initiated due to the presence of a free charge, i.e., free electrons. In some of these display devices, especially where background radiation and thermionic emission are employed to produce the necessary initiating charge, the free charge may not be present until an undesirably long time has passed so as to limit the addressing time of the display device. The problem of slow addressing time is most acute in device applications which are to provide television type viewing since, for example, cells should be capable of a rapid repetition rate, i.e., one-thirtieth or one-sixtieth of a second. In addition, depending upon the particular addressing scheme employed, e.g., line-at-a-time addressing, the cell must be capable of assuming its full "on" position within an extremely short time period, i.e., less than 1 .mu.sec after the cell is turned on in the case of certain line addressing schemes. Thus, it would be desirable to develop a display device in which means are provided for ensuring the presence of free charge so as to allow rapid addressing.